 claude-noether
|
df787a6cc2
|
iter2 Phase 8 close: 3/5 codecs passing, lesson L1 extended (BOTH directions)
Iteration 2 closes with all 5 Phase 1 boolean-correctness criteria
green. Third codec passes — campaign scoreboard 2/5 → 3/5 (H.264
in T4, MPEG-2 in iter1, HEVC in iter2). Loop terminates per
feedback_dev_process.md Phase 8.
Notable: ZERO Phase 7 → Phase 4 loopbacks needed. Phase 5 review
caught all 3 would-be loopback triggers in advance (data_byte_offset
rename, dpb.rps→index-arrays semantics, pic_order_cnt_val rename).
This is the dev-process ideal: review catches bugs before
implementation lands; verification confirms contract.
What landed:
Code (libva-v4l2-request-fourier master 229d6d1 → 8d71e20):
cca539d iter2 Phase 6 commit A: config.c break for HEVCMain case
8d71e20 iter2 Phase 6 commit B: rewrite h265.c against new V4L2
stateless HEVC API (6 files, 463 ins, 236 del)
Both authored as Claude (noether) per feedback_gitea_as_claude_noether.md.
Campaign docs (fresnel-fourier):
6e8c970 iter2 Phase 0 + Phase 1 lock
b3ba157 iter2 Phase 2 situation analysis (6 bugs)
d35a247 iter2 Phase 3 baselines (substrate post-pacman-Syu + HEVC anchor)
348736e iter2 Phase 4 plan (10 contract clauses)
9eae068 iter2 Phase 5 sonnet review (3 Critical UAPI errors caught)
05b4bd5 iter2 Phase 7 verification (5/5 GREEN)
[this commit] iter2 Phase 8 close
Lesson L1 distilled to memory (extension of iter1 entry):
feedback_review_empirical_over_theoretical.md updated with
Direction 2 corollary. Original iter1 lesson covered
author-rebuttal-of-reviewer-finding (lean empirical, defer to
Phase 7 byte-compare). iter2 surfaced opposite direction:
author-too-credulously-adopting-reviewer-amendment.
Concrete iter2 instance: Phase 5 S1 suggested
picture->pic_fields.bits.uniform_spacing_flag exists in VAAPI as
source for V4L2_HEVC_PPS_FLAG_UNIFORM_SPACING. I adopted into
amended plan without verifying. Phase 6 build failed:
error: struct has no member named 'uniform_spacing_flag'
VAAPI's VAPictureParameterBufferHEVC doesn't expose either bit
19 or bit 20. Reviewer-cited mapping was wrong; cheap gcc
test-compile would have caught it.
Memory updated with Direction 2 protocol: when reviewer
suggests a field mapping, verify empirically (test-compile,
struct dump, kernel UAPI grep) BEFORE incorporating into the
amended plan. Generalized rule: empirical evidence trumps
source-read theory in BOTH directions of Phase 5 review.
Backlog items deferred (campaign-internal, not durable memory):
B6 — VAAPI ↔ V4L2 SPS field-fidelity gaps:
sps_max_num_reorder_pics (post-fix=0, baseline=2),
sps_max_latency_increase_plus1 (post-fix=0, baseline=4),
possibly PPS bit 12 ENTROPY_CODING_SYNC_ENABLED.
VAAPI doesn't expose; FFmpeg parses from bitstream directly.
Operational impact NIL (Phase 7 Criterion 4 byte-identical
pixel pass). Phase 8 polish-backlog candidate: add SPS
bitstream parsing to h265_fill_sps when VAAPI doesn't supply
the fields. Probably low ROI — kernel HEVC handler tolerates
0 values for the BBB fixture. Defer until a real-world consumer
surfaces a fixture that breaks on this.
B7 — Phase 4 plan body sizeof typo:
Plan claimed sizeof(scaling_matrix) = 1296. Empirical = 1000
bytes. Code uses sizeof() symbolically so produces correct
bytes; only plan body's expected-value comment was wrong.
Phase 7 byte-compare structural check caught it. Future polish:
state struct sizes via sizeof() references in plan bodies, not
hand-computed values.
iter1 carryover backlog (still deferred):
B3 latent surface-reuse bug — picture.c:287 h264.matrix_set=false
hits union byte 240. For HEVC: byte 240 lands in h265.picture.
RenderPicture's per-frame VAPictureParameterBufferType
overwrite masks the corruption (verified Phase 5 Q3 — mpv-vaapi
sends VAPictureParameterBufferType per frame for HEVC, no
MPEG-2-style filtering). Iter2+ Phase 4 cross-cutting candidate.
B4 context.c H.264 device-init log noise (rkvdec accepts both
H.264 + HEVC controls cleanly; on hantro both EINVAL with
cosmetic log). Iter2 added a 2nd batched call for HEVC; same
(void) swallow pattern. Cosmetic.
B5 vbv_buffer_size 1MB vs 1.31MB (MPEG-2-only; not exercised by
HEVC).
Phase 4 cross-cutting work items collected:
- VIDIOC_EXPBUF + DMA_BUF_IOCTL_SYNC for vaDeriveImage cache-stale
fix (still applies to all codecs)
- V4L2 device-discovery probe (still applies)
- picture.c BeginPicture profile-aware reset (B3)
- context.c H.264+HEVC device-init log suppression (B4)
- mpeg2 vbv_buffer_size negotiation polish (B5)
- h265 SPS bitstream-parse fidelity polish (B6)
Campaign roadmap (codec iterations remaining):
iter3: VP8 on hantro — implement vp8.c. Smaller scope than iter2;
predicting closer to iter1 MPEG-2 in size. No slice_params
dynamic-array; single v4l2_ctrl_vp8_frame struct per kernel
UAPI.
iter4: VP9 on rkvdec — implement vp9.c. Largest control surface
remaining.
Phase 5 review value confirmed empirically AGAIN: 3 Critical findings
caught (data_byte_offset rename, dpb.rps→index-arrays semantics,
pic_order_cnt_val rename) — would have been Phase 6 compile failures
or silent semantic bugs. Without that review pass, iter2 would have
required at least 1-2 Phase 7 → Phase 4 loopback cycles. Reviews
are never skippable per global ~/.claude/CLAUDE.md rule; iter2
exemplifies why.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
|
2026-05-08 15:16:55 +00:00 |
|